The correct spelling is "combustible." It refers to a substance that is capable of catching fire and burning easily.
No, argon is not flammable or combustible because it is an inert gas.
Batman's notable enemies are The Joker, The Riddler, The Penguin, Bane, The Scaregrow, Harley Quinn, The Mad Hatter, Mr. Freeze, Poison ivy, Ra's al Ghul and Two-Face however other villains that would include all of the official Batman mythology would include ones such as Abattoir, Amba Kadiri, Amygdala, Scorn, Dr. Falsario, Mister Bygone, The Professor, Wolf-Spider, Brute, Volt, Fishnet, Malicia, Mister Toxic, Mr. Combustile, Emperor Blackgate and Imperceptible Man.
Combustible fabrics can catch fire and combust, unlike the latter.